///******************************************************************************
// *  Compilation:  javac TST.java
// *  Execution:    java TST < words.txt
// *  Dependencies: StdIn.java
// *  Data files:   https://algs4.cs.princeton.edu/52trie/shellsST.txt
// *
// *  Symbol table with string keys, implemented using a ternary search
// *  trie (TST).
// *
// *
// *  % java TST < shellsST.txt
// *  keys(""):
// *  by 4
// *  sea 6
// *  sells 1
// *  she 0
// *  shells 3
// *  shore 7
// *  the 5
// *
// *  longestPrefixOf("shellsort"):
// *  shells
// *
// *  keysWithPrefix("shor"):
// *  shore
// *
// *  keysThatMatch(".he.l."):
// *  shells
// *
// *  % java TST
// *  theory the now is the time for all good men
// *
// *  Remarks
// *  --------
// *    - can't use a key that is the empty string ""
// *
// ******************************************************************************/
//
//package com.dennis.algs4.string;
//
///**
// *  The {@code TST} class represents an symbol table of key-value
// *  pairs, with string keys and generic values.
// *  It supports the usual <em>put</em>, <em>get</em>, <em>contains</em>,
// *  <em>delete</em>, <em>size</em>, and <em>is-empty</em> methods.
// *  It also provides character-based methods for finding the string
// *  in the symbol table that is the <em>longest prefix</em> of a given prefix,
// *  finding all strings in the symbol table that <em>start with</em> a given prefix,
// *  and finding all strings in the symbol table that <em>match</em> a given pattern.
// *  A symbol table implements the <em>associative array</em> abstraction:
// *  when associating a value with a key that is already in the symbol table,
// *  the convention is to replace the old value with the new value.
// *  Unlike {@link java.util.Map}, this class uses the convention that
// *  values cannot be {@code null}—setting the
// *  value associated with a key to {@code null} is equivalent to deleting the key
// *  from the symbol table.
// *  <p>
// *  This implementation uses a ternary search trie.
// *  <p>
// *  For additional documentation, see <a href="https://algs4.cs.princeton.edu/52trie">Section 5.2</a> of
// *  <i>Algorithms, 4th Edition</i> by Robert Sedgewick and Kevin Wayne.
// */
//public class TST<Value> {
//    private int n;              // size
//    private Node<Value> root;   // root of TST
//
//    private static class Node<Value> {
//        private char c;                        // character
//        private Node<Value> left, mid, right;  // left, middle, and right subtries
//        private Value val;                     // value associated with string
//    }
//
//    /**
//     * Initializes an empty string symbol table.
//     */
//    public TST() {
//    }
//
//    /**
//     * Returns the number of key-value pairs in this symbol table.
//     * @return the number of key-value pairs in this symbol table
//     */
//    public int size() {
//        return n;
//    }
//
//    /**
//     * Does this symbol table contain the given key?
//     * @param key the key
//     * @return {@code true} if this symbol table contains {@code key} and
//     *     {@code false} otherwise
//     * @throws IllegalArgumentException if {@code key} is {@code null}
//     */
//    public boolean contains(String key) {
//        if (key == null) {
//            throw new IllegalArgumentException("argument to contains() is null");
//        }
//        return get(key) != null;
//    }
//
//    /**
//     * Returns the value associated with the given key.
//     * @param key the key
//     * @return the value associated with the given key if the key is in the symbol table
//     *     and {@code null} if the key is not in the symbol table
//     * @throws IllegalArgumentException if {@code key} is {@code null}
//     */
//    public Value get(String key) {
//        if (key == null) {
//            throw new IllegalArgumentException("calls get() with null argument");
//        }
//        if (key.length() == 0) throw new IllegalArgumentException("key must have length >= 1");
//        Node<Value> x = get(root, key, 0);
//        if (x == null) return null;
//        return x.val;
//    }
//
//    // return subtrie corresponding to given key
//    private Node<Value> get(Node<Value> x, String key, int d) {
//        if (x == null) return null;
//        if (key.length() == 0) throw new IllegalArgumentException("key must have length >= 1");
//        char c = key.charAt(d);
//        if      (c < x.c)              return get(x.left,  key, d);
//        else if (c > x.c)              return get(x.right, key, d);
//        else if (d < key.length() - 1) return get(x.mid,   key, d+1);
//        else                           return x;
//    }
//
//    /**
//     * Inserts the key-value pair into the symbol table, overwriting the old value
//     * with the new value if the key is already in the symbol table.
//     * If the value is {@code null}, this effectively deletes the key from the symbol table.
//     * @param key the key
//     * @param val the value
//     * @throws IllegalArgumentException if {@code key} is {@code null}
//     */
//    public void put(String key, Value val) {
//        if (key == null) {
//            throw new IllegalArgumentException("calls put() with null key");
//        }
//        if (!contains(key)) n++;
//        else if(val == null) n--;       // delete existing key
//        root = put(root, key, val, 0);
//    }
//
//    private Node<Value> put(Node<Value> x, String key, Value val, int d) {
//        char c = key.charAt(d);
//        if (x == null) {
//            x = new Node<Value>();
//            x.c = c;
//        }
//        if      (c < x.c)               x.left  = put(x.left,  key, val, d);
//        else if (c > x.c)               x.right = put(x.right, key, val, d);
//        // 没有走到单词位，查找未完成
//        else if (d < key.length() - 1)  x.mid   = put(x.mid,   key, val, d+1);
//        else                            x.val   = val;
//        return x;
//    }
//
//    /**
//     * Returns the string in the symbol table that is the longest prefix of {@code query},
//     * or {@code null}, if no such string.
//     * @param query the query string
//     * @return the string in the symbol table that is the longest prefix of {@code query},
//     *     or {@code null} if no such string
//     * @throws IllegalArgumentException if {@code query} is {@code null}
//     */
//    public String longestPrefixOf(String query) {
//        if (query == null) {
//            throw new IllegalArgumentException("calls longestPrefixOf() with null argument");
//        }
//        if (query.length() == 0) return null;
//        int length = 0;
//        Node<Value> x = root;
//        int i = 0;
//        while (x != null && i < query.length()) {
//            char c = query.charAt(i);
//            if      (c < x.c) x = x.left;
//            else if (c > x.c) x = x.right;
//            else {
//                i++;
//                if (x.val != null) length = i;
//                x = x.mid;
//            }
//        }
//        return query.substring(0, length);
//    }
//
//    /**
//     * Returns all keys in the symbol table as an {@code Iterable}.
//     * To iterate over all of the keys in the symbol table named {@code st},
//     * use the foreach notation: {@code for (Key key : st.keys())}.
//     * @return all keys in the symbol table as an {@code Iterable}
//     */
//    public Iterable<String> keys() {
//        Queue<String> queue = new Queue<String>();
//        collect(root, new StringBuilder(), queue);
//        return queue;
//    }
//
//    /**
//     * Returns all of the keys in the set that start with {@code prefix}.
//     * @param prefix the prefix
//     * @return all of the keys in the set that start with {@code prefix},
//     *     as an iterable
//     * @throws IllegalArgumentException if {@code prefix} is {@code null}
//     */
//    public Iterable<String> keysWithPrefix(String prefix) {
//        if (prefix == null) {
//            throw new IllegalArgumentException("calls keysWithPrefix() with null argument");
//        }
//        Queue<String> queue = new Queue<String>();
//        Node<Value> x = get(root, prefix, 0);
//        if (x == null) return queue;
//        if (x.val != null) queue.enqueue(prefix);
//        collect(x.mid, new StringBuilder(prefix), queue);
//        return queue;
//    }
//
//    // all keys in subtrie rooted at x with given prefix
//    private void collect(Node<Value> x, StringBuilder prefix, Queue<String> queue) {
//        if (x == null) return;
//        collect(x.left,  prefix, queue);
//        if (x.val != null) queue.enqueue(prefix.toString() + x.c);
//        collect(x.mid,   prefix.append(x.c), queue);
//        prefix.deleteCharAt(prefix.length() - 1);
//        collect(x.right, prefix, queue);
//    }
//
//
//    /**
//     * Returns all of the keys in the symbol table that match {@code pattern},
//     * where . symbol is treated as a wildcard character.
//     * @param pattern the pattern
//     * @return all of the keys in the symbol table that match {@code pattern},
//     *     as an iterable, where . is treated as a wildcard character.
//     */
//    public Iterable<String> keysThatMatch(String pattern) {
//        Queue<String> queue = new Queue<String>();
//        collect(root, new StringBuilder(), 0, pattern, queue);
//        return queue;
//    }
//
//    private void collect(Node<Value> x, StringBuilder prefix, int i, String pattern, Queue<String> queue) {
//        if (x == null) return;
//        char c = pattern.charAt(i);
//        if (c == '.' || c < x.c) collect(x.left, prefix, i, pattern, queue);
//        if (c == '.' || c == x.c) {
//            if (i == pattern.length() - 1 && x.val != null) queue.enqueue(prefix.toString() + x.c);
//            if (i < pattern.length() - 1) {
//                collect(x.mid, prefix.append(x.c), i+1, pattern, queue);
//                prefix.deleteCharAt(prefix.length() - 1);
//            }
//        }
//        if (c == '.' || c > x.c) collect(x.right, prefix, i, pattern, queue);
//    }
//
//
//    /**
//     * Unit tests the {@code TST} data type.
//     *
//     * @param args the command-line arguments
//     */
//    public static void main(String[] args) {
//
//        // build symbol table from standard input
//        edu.princeton.cs.algs4.TST<Integer> st = new edu.princeton.cs.algs4.TST<Integer>();
//        for (int i = 0; !StdIn.isEmpty(); i++) {
//            String key = StdIn.readString();
//            st.put(key, i);
//        }
//
//        // print results
//        if (st.size() < 100) {
//            StdOut.println("keys(\"\"):");
//            for (String key : st.keys()) {
//                StdOut.println(key + " " + st.get(key));
//            }
//            StdOut.println();
//        }
//
//        StdOut.println("longestPrefixOf(\"shellsort\"):");
//        StdOut.println(st.longestPrefixOf("shellsort"));
//        StdOut.println();
//
//        StdOut.println("longestPrefixOf(\"shell\"):");
//        StdOut.println(st.longestPrefixOf("shell"));
//        StdOut.println();
//
//        StdOut.println("keysWithPrefix(\"shor\"):");
//        for (String s : st.keysWithPrefix("shor"))
//            StdOut.println(s);
//        StdOut.println();
//
//        StdOut.println("keysThatMatch(\".he.l.\"):");
//        for (String s : st.keysThatMatch(".he.l."))
//            StdOut.println(s);
//    }
//}
//
///******************************************************************************
// *  Copyright 2002-2020, Robert Sedgewick and Kevin Wayne.
// *
// *  This file is part of algs4.jar, which accompanies the textbook
// *
// *      Algorithms, 4th edition by Robert Sedgewick and Kevin Wayne,
// *      Addison-Wesley Professional, 2011, ISBN 0-321-57351-X.
// *      http://algs4.cs.princeton.edu
// *
// *
// *  algs4.jar is free software: you can redistribute it and/or modify
// *  it under the terms of the GNU General Public License as published by
// *  the Free Software Foundation, either version 3 of the License, or
// *  (at your option) any later version.
// *
// *  algs4.jar is distributed in the hope that it will be useful,
// *  but WITHOUT ANY WARRANTY; without even the implied warranty of
// *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// *  GNU General Public License for more details.
// *
// *  You should have received a copy of the GNU General Public License
// *  along with algs4.jar.  If not, see http://www.gnu.org/licenses.
// ******************************************************************************/
